Many industries require large quantities of air or other fluids to be moved as part of their processes. For example, in the electric power generation industry, pulverized coal and air are moved through conduits (ductwork) which can be as large as eight feet in diameter towards a furnace in which combustion occurs. Maintaining the proper coal/air ratio is important in order to optimize the amount of power generated but also to minimize the amount of pollutants that are created as a by-product of said combustion. However, as is well-known to those skilled in the art, the conduit, especially as it nears the furnace, is rarely straight for distances which are long enough to afford accurate measurements using conventional techniques.
The measurement of fluid flow in non-linear ductwork is a well-known problem. This is due to the fact that when a fluid (such as air) is directed around a corner, fluid flow is disturbed and a portion of the fluid is actually flowing in the reverse direction. This is especially true at or near a take off point (a split in the conduit). The aforementioned reversal continues for approximately four to seven conduit diameters.
In the prior art, nozzle pitots have been installed in a nozzle positioned in the conduit in an attempt to measure fluid flow. Unfortunately, the diameter of the nozzle is such that the volume of fluid is substantially reduced which causes a pressure loss across the nozzle. For example, given an eight foot diameter conduit having an air flow rate of 4000 feet/min. generates 5 inches of water pressure with a 1000 hp fan. If the nozzle doubles the pressure, then a 2000 hp fan is required in order to maintain the same air flow rate. Another method of measuring air flow is to locate a honeycomb type structure in the conduit in order to straighten the fluid flow prior to measurement by a conventional pitot. This method also suffers from a pressure drop and additionally, the honeycombs tend to become clogged, which further degrades performance.
Thus, it will be seen that unrecovered pressure losses result in system losses in the form of heat or decreased system efficiency.
In view of the foregoing, it would be of great commercial value to provide an improved fluid flow measurement apparatus.
Accordingly, it is an object of the present invention to provide an improved fluid flow measurement apparatus.
Another object of the present invention is to provide an improved fluid flow measurement apparatus which operates in short conduit sections.
A further object of the present invention is to provide an improved fluid flow measurement apparatus which acts to straighten fluid flow.
A still further object of the present invention is to provide an improved fluid flow measurement apparatus which minimizes pressure drop.
Yet another object of the present invention is to provide an improved fluid flow measurement apparatus which is inexpensive.
An additional object of the present invention is to provide an improved fluid flow measurement apparatus which is accurate.